JAW's Cable Selection Calculator

Choose the right cable, according to Australian Standard AS3000. The cross sectional area (CSA)
of a conductor will cause a volt drop per meter per amp. To be compliant, the cable should have no
more than 5% volt drop over its total length for full load current and no more than 10% volt drop
for start up current. A rule of thumb for a motor is the start up current is 5 times the full load
current.

Example: You want to run a cable for a powerpoint in your shed 100m away. You
may only pull 10A from a power point so that becomes the full load current. Lets say the biggest
power tool you are going to run has a 1200W motor; divide that by 230(volts) gives you its full load
requirement at 5.2A. Start up current for a motor is five times the full load current so the tool
will draw 26A on startup. The calculator shows that although 4mm&sup2 cable is fine for the full load
current, only a 6mm&sup2 cable meets the specification for start up current.

* Distance:

m

* Full Load Current:

A

* Start Up Current:

A

CSA

Max Amps

Amp metre
Volt Drop

Full Load Volt Drop

Start Up Volt Drop

mm&sup2

A

mV

V

%

V

%

2.5

27

17.3

4

36

11

6

46

7.35

10

64

4.37

16

85

2.75

25

120

1.62

Always remember that the right insulated cable must be used, correctly installed, correctly earthed, correctly protected, etc etc, as per AS3000. To get really serious about your cable
selection check out www.as3008.com.